Improvement in pressure-gages



J. B. EADS & H. FLAD.-

Improvement in Pressure-Gauges.

`Patenned Aug.20, 1872.

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UNITED STATES PATENT OFFICE.

JAMES E. EADS AND EENEY EDAD, oE ST. LOUIS, MISSOURI.

IMPROVEMENT IN PR'ESSURE-GAGES.

Specification forming part of Letters Patent No. 130,705, dated August20, 1872.

Specification describing a certain Improve me it in PressureGages,invented by JAMES B. EADS and HENRY FLAD, both of the city and county ofSt. Louis and State of Missouri.

This improvement consists in the attachment of a piston similarto thatof a hydraulic ram to a spring within the chamber ofthe cylinder, thespring tending to draw the piston inward and the pressure of the fluidwithin the cylinder forcing the piston outward. The movement of thepiston is indicated by a similar arrangement to that of our patent No.117 ,394, dated July 25, 1871.

Figures 1 and 2 are axial sections of our improvement. Fig. 3 is a planof the supportin g-fork of the indicator in Fig. 2.

A is the cylinder containing the spring B, secured at each end in anysuitable manner.

' We propose to support the ends of the bar inL rin gs C having roundedor knife edge bearin gs c c for the bar, the lower bearin g c beingsomewhat nearer to the middle of the bar so as not to pinch the bar inthe bending of the latter upward. D is the cylinder of the piston E,whose upper end e projects from the cylinder and turns an indicator, f,similarly arranged to that in our patent No. 117 ,394, to whichreference is made for description of The piston may be made of anydesired size and the spring of any suitable strength, so as to indicateeither high or low pressures. In some cases, particularly when Yveryhigh pressures are to be gaged, the piston would not have greatersectional area than the portion e connecting the piston proper E to thespring B. The spring B may be of prismatic or of any suitable form, ormay be enlarged at the point of the greatest strain;

and the metal composing it may be round or angular in section. Thechamber S oi' the cylinders may be lled with liquid; or vapor (from aSteam-boiler, for instance) maybe allowed to enter, but we prefer to useliquid as the medium acting directly upon the piston. F is the pipethrough which the pressure is communicated to the gage. G is a stop-cockin the pipe F. g is a shifting or escape cock in the cylinder. Theobject of these cocks is to enable the reduction of the pressure withinthe chamber S to that of the outer atmosphere by first closing the cockGr to cut oli communication between the gage and the hydraulic ram,steamboiler, 85e., and then opening the cock g to reduce the pressurewithin the chamber S. The nger f may then be adjusted to the zero-markit' it prove to be out of place.

In Fig. 2 the pistons E are attached to'the upper ends of the xedsprings B. The action is similar to that shown in Fig. 1; but themovement of the finger f would be twice as great, because it is heldbetween the two moving rods e e" forming the projecting portions of thepistons. These rods have return bends, as shown, and the end of thelower-one is forked, as shown in Fig. 3, so as to make a good bearingfor the cylindrical part of the indicator.

The employment of the friction of bent rods pressing on a roller tooperate the indicator has several advantages over the use of the rackand pinion, or their equivalents, among' which may be mentioned theobviatin g oi' fric tion at the pivotal point of the pinion and theeXtreme sensitiveness of t-he parts, by means of which the smallestpressures are indicated, which the play of the pinion in the rack wouldprevent in the use of the latter gear. These dierences in operationrender the employment of the friction-gear more advantageous than therack and pinion or their equivalents. We are aware, however, thatfrictiongear, per se, is not new; but by our construction of rebendingthe rods we are enabled to get twice the range oi' motion of ourindicator as is attained in the friction-gear, where but one rod androller are employed, while, at the same time, we obtain all theadvantages of the sensitive friction-gear.

Ve claim as new and of our invention- The rebent rods e e, pistons E E,connecting-rods e e', roller-spindle f', and indicator in combina-tionwith the springs B B, whereby the movement of the indicator would betwice as great as when one rod is used, Substantially as described. y

In testimony oi' which invention we have hereunto set our hands.

JAS. B. EADS. HENRY FIIAD. 'Witnessesz SAME. KNIGHT,

JAMES ANDREWS.

